2-Keto-L-gulonic acid (hereinafter referred to as 2KLGA) is a key intermediate in the synthesis of L-ascorbic acid. For industrial production, 2KLGA is chemically synthesized from L-sorbose by oxidation according to the Reichstein's method.
On the other hand, it is well known that many microorganisms have an ability to convert L-sorbose to 2KLGA through a two-step enzymatic oxidation by SDH and SNDH. Namely, SDH catalyzes the oxidation of L-sorbose to L-sorbosone, and SNDH catalyzes the oxidation of L-sorbosone to 2KLGA. However, because of the low productivity of 2KLGA obtained by using these microorganisms, they have not been applied to the industrial production yet.
It is desirable to provide efficient and simplified methods for the production of 2KLGA.